RADIATION PROTECTION

Environmental radiation surveys carried out in China and further suggestions

CHEN Qianyuan, YANG Weigeng, ZHAO Shunping, ZHENG Huidi, CHEN Bin, SONG Weigang

RADIATION PROTECTION. 2021, 41(6): 481-487.

Abstract ( 234 )

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Aiming to evaluate the necessity of carrying out the 2nd nationwide environmental radiation level survey, the environmental monitoring surveys carried out ever since the 1st nationwide natural radiation level survey were investigated, among which monitoring objects or environmental medias, monitoring items and the coverage of monitoring sites of each survey were analyzed. Several shortages were found, for example, data for air sample and biological sample are insufficient, activity concentration of artificial radionuclides needs to be further investigated, coverage of marine monitoring requires improvement, radon concentration survey wasn't paid adequate attention, terrestrial aquatic radioactivity survey needs to be further strengthened, etc. In summary, in the nearest future, establishment of environmental survey database, correspondent surveys for compensating the previous shortages should be the focused. Therefore, the 2nd nationwide survey was not suggested to be carried out currently.

Discussion on the release limits of ¹⁴C in effluent from pressurized water reactor NPP

SHANGGUAN Zhihong, HUANG Yanjun, JIANG Jing, ZHU Zhaowen, LIU Xinhua

RADIATION PROTECTION. 2021, 41(6): 488-495.

Abstract ( 123 )

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In this paper, the source of ¹⁴C in the reactor and the coolant of pressurized water reactor (PWR) nuclear power plant (NPP) was analyzed, and the release level of ¹⁴C in the effluent for PWR-NPPs in the USA and Europe was investigated. The envelope ability of the current limits of ¹⁴C annual release stipulated by national standard GB 6249—2011 were analyzed, based on the long-years of realistically reported release data. Meanwhile, the possible increasing of ¹⁴C release for AP1000 and EPR NPP units compared the traditional PWR was investigated, which should be paid attention for the discharge limit setting especially for multi-units NPP sites. Besides, the ¹⁴C application in the various fields, such as the biology and medicine science were briefly introduced. It was shown the recovery of ¹⁴C in the gaseous effluent of PWR-NPP is essential and significant to produce economic benefits, as well as the social benefits basically, which could reduce public dose dramatically for the local individuals.

Analysis on standards for high level radioactive waste treatment and disposal

LIU Lipo, LI Xiaozhen, JIN Liqiang, LIU Fugui

RADIATION PROTECTION. 2021, 41(6): 496-502.

Abstract ( 169 )

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The importance of standards for high-level radioactive waste treatment and disposal in China was described in this paper. The current situation of standards for high-level radioactive waste treatment and disposal at home and abroad was described and analyzed. The standardization problem regarding high-level radioactive waste treatment and disposal standard system, high-level radioactive liquid waste source term analysis, high-level radioactive liquid waste vitrified body performance requirements and test methods, engineering economy of high-level radioactive waste treatment and disposal, deep geological disposal of high-level radioactive waste etc., were studied and analyzed. Opinions and suggestions on standardization of high-level radioactive waste treatment and disposal were put forward.

Case study of inner leakage rate test in nuclear power station MCR

TIAN Lei, CHEN Wenqiang

RADIATION PROTECTION. 2021, 41(6): 503-507.

Abstract ( 149 )

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This paper mainly discusses the first application of constant injection test method to measure the inner leakage rate of MCR in domestic nuclear power plant. Through research for calculation principle of inner leakage rate, injection rate and the balance judgment criterion, the suitable tracer gas, suitable injection point and injection rate are selected for the first test domestically. Some key influential factors are also investegated in order to solve the problems of design and construction. This test method has good reproducibility and can be applied in other domestic nuclear power plants.

Research on layout method for nuclear criticality accident alarm system

SHAO Zeng, HUO Xiaodong, YI Xuan, LIU Guoming, YANG Haifeng

RADIATION PROTECTION. 2021, 41(6): 508-513.

Abstract ( 164 )

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This paper expounds the significance and principle of the layout of nuclear criticality accident alarm system in spent fuel reprocessing plant, analyzes the mechanism of potential nuclear criticality accident, and preliminarily establishes a set of scenario hypothesis analysis method for nuclear criticality accident. The calculation method of the source term of the minimum criticality accident and tallying of three-dimensional dose field distribution of equipment room is studied. The method of contour plot of the minimum criticality accident dose field distribution of all equipment is applied to optimize selecting the appropriate location of the nuclear criticality accident alarm system from many dose field distribution maps, so as to ensure that all equipment with nuclear criticality accident risk can be covered. The principle and specific method of probe type selection of the nuclear criticality accident alarm system are also analyzed.

Study on vadose-saturation zone coupling simulation of radionuclide migration

ZHANG Xue, HU Jihua, SHI Xiaowen, WANG Xiaoyuan

RADIATION PROTECTION. 2021, 41(6): 514-522.

Abstract ( 127 )

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In order to obtain more real environmental impact assessment results for groundwater,a simulation study on vadose-saturation zone coupling was carried out by using quasi-three-dimensional method based on experiment and numerical simulation. To further explain the hysteresis effect of vadose medium on nuclides migration, simulation without considering the vadose medium was carried out and the results was compared with that of the coupling simulation. The results show that: (1) For strong adsorbed Se-79, Pd-107, Cs-135 and Sn-126, their concentration arriving at water table is far less than the leaked liquid due to the hysteresis effect. And their annual committed effective dose for public will be less than the dose limit of 0.1 mSv. For weakly adsorbed C-14, the annual committed effective dose for public will be more than 0.1 mSv and it requires coupling simulation. (2) C-14 migrates to downstream by convection, and pollution range increases through dispersion. At the same time the C-14 concentration decreases by dilution, decay and adsorption, therefore the annual committed effective dose for public will be less than 0.1 mSv. (3) The concentration of C-14 in groundwater decreases greatly and the migration distance decreases obviously because of the hysteresis effect of vadose medium on nuclides migration. The peak concentration of C-14 in groundwater is 2.15 Bq/L taking vadose zone into consideration; while leaving out the vadose zone, the peak concentration of C-14 will be 9.4×10⁴ Bq/L.The migration distance of C-14 is 1.5 m, 4 m and 4.2 m respectively in 1, 5 and 10 years after the accident, taking vadose zone into consideration; while leaving out the vadose zone, the migration distance of C-14 will be 3 m, 12 m and 17 m respectively.

Capacity analysis and optimization of the hydrogenen containing gaseous waste treatment process for M310 NPP

DONG Liang, LIU Hongkun, TANG Hui, LIU Yiming, LIU Yan

RADIATION PROTECTION. 2021, 41(6): 523-529.

Abstract ( 133 )

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Hydrogen containing gaseous waste from primary loop consists of hydrogen and radionuclides. Radionuclides include ⁸⁵Kr, ^85mKr, ⁸⁸Kr, ¹³³Xe, and ¹³⁵Xe, as well as small amount of ¹³¹I, ¹³²I, ¹³³I, ¹³⁵I, ¹³²Te etc. Due to shortage of decay box capacity, the purge operation of the reactor coolant system and the overhaul process are affected and hydrogen leakage risk is also created. Pressurized storage decay treatment process which has been widely used to treat hydrogenous gaseous radioactive waste in M310 NPPs needs to be modified and optimized. In this paper, based on hydrogen sources, through the investigation of various normal operating conditions, operating specifications and standards, the gas emission quantity and components ratio were analyzed. We concluded that the key factors are the purge operation of volume control tank and the reactor coolant system. Peak gas flow and total volume, and the volume ratio of hydrogen are shown through the Calculation. Reasonable capacities of different processes are proposed at last, avoiding economic waste caused by excessive redundancy.

Laboratory hot test verification of wet oxidation process of radioactive spent resin

YAN Xiaojun, LIU Zhaofeng, GUO Xiliang, XI Yahui, XUE Hailong, WANG Zhiwei

RADIATION PROTECTION. 2021, 41(6): 530-535.

Abstract ( 126 )

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Using 1 kg spent resin wet oxidation bench, the feasibility hot test of spent resin wet oxidation process was carried out in a nuclear power base. The effect of real spent resin wet oxidation treatment was verified, and the safety of waste gas emission of the process system was evaluated. The contact dose rate of spent resin used in the test is 602-680 Sv/h, and the treatment capacity of spent resin in a single test is 1 kg. The results show that the decomposition rate of spent resin is more than 99% (calculated by COD value), and the carrying rate of tail gas for main nuclides ⁶⁰Co, ⁵⁴Mn, ¹³⁷Cs and ⁹⁰Sr is less than 0.001%. This study laid a solid foundation for further research on wet oxidation process of spent resin and scale-up of the testing device.

Study on “Activated Carbon Pressurized Adsorption” for NPPs' radioactive gaseous wastes

FAN Wenwen, WANG Yilin, GAO Ruifa

RADIATION PROTECTION. 2021, 41(6): 536-541.

Abstract ( 160 )

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The gaseous waste source of ACP100 was introduced for the difference analysis with “Activated Carbon Pressurized Adsorption”, M310 pressured storage and AP1000/VVER atmospheric pressure adsorption. It was found that the needed carbon loading of the “pressurized and activated carbon delayed decay” process decreased by 75% compared with that of the atmospheric pressure adsorption and the decay volume decreased by 92% compared with that of the pressurized storage. The radioactivity concentration of the treated waste gas decreased by 47% and 93% respectively compared with that of the M310 and AP1000. The amount of secondary waste is small, and the design value for secondary solid waste generation is 1.2 m³/a. In summary, the “pressured and activated carbon delayed decay” gaseous waste treatment process not only solves the existing technical trouble, but also has good purification effect, low secondary waste generation, small floor space, as well as good economic benefits, etc. This process can be applied and promoted in other NPPs.

The emergency preparedness categories and corresponding requirements of nuclear and radiation emergency

ZHANG Jiangang, LI Guoqiang, YANG Yapeng, FENG Zongyang, JIA Linsheng, WANG Ning, LIANG Boning, LIU Yining, ZHU Yeming

RADIATION PROTECTION. 2021, 41(6): 542-549.

Abstract ( 175 )

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The article describes emergency preparedness categories based on the hazard according to the international experience, and the ability that all classifications of emergency preparedness need to establish, and puts forward the management recommendations of 11 main elements including emergency management actions, emergency conditions, start of emergency response, mitigation actions, emergency assessment and prognosis, protection actions and other response actions, the public emergency information, protection measurements of emergency workers and emergency helpers, medical response actions, and emergency organizations and staffing, corresponding to 5 categories of emergency preparedness.

The role of miR-200b in radiation-induced thymic lymphoma and its preliminary mechanism

YE Hui, FENG Zhelan, CHENG Ying, CAI Jianming, JIANG Jianming

RADIATION PROTECTION. 2021, 41(6): 550-557.

Abstract ( 108 )

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In order to explore the role and mechanism of miR-200b in radiation-induced thymic lymphoma, the radiation-induced thymic lymphoma model of BALB/c mice was established by whole body fractionated irradiation. The expression of miR-200b was detected, and the over expression and knockdown miR-200b cell model was constructed to detect the effect of miRNA on cell proliferation and apoptosis. Then the potential targets of miRNA were analyzed by miRNA database TargetScan and verified by dual luciferase reporter system. Finally, the correlation between TBK1 protein and miR-200b expression was analyzed by Spearman method. The results showed that the expression of miR-200b in mice thymic lymphoma was down-regulated by radiation, over expression of miR-200b could significantly inhibit cell proliferation and promote apoptosis, while down-regulation of miR-200b could promote cell proliferation and inhibit apoptosis, and dual luciferase reporting system suggested that miR-200b targeted TBK1 in a 3'UTR-dependent manner. In radiation-induced thymic lymphoma samples, there was a negative correlation between the expression of miR-200b and the level of TBK1 protein, and the over expression of TBK1 could partially reverse the cellular biological effects mediated by miR-200b. The results showed that the expression of miR-200b was down-regulated and the direct target TBK1 was up-regulated in thymic lymphoma induced by radiation, and the over expression of miR-200b could significantly inhibit the proliferation and increase the apoptosis of thymic lymphoma cells. It is suggested that targeted regulation of miR-200b/TBK1 may be a potential new approach to prevent and treat radiation-induced thymic lymphoma.

The study of DCs in the assessment of non-human species

GONG Wenjing, WANG Huijuan

RADIATION PROTECTION. 2021, 41(6): 558-564.

Abstract ( 102 )

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In the assessment of radiation effects on non-human species, the organism model is an important basis for dose assessment. In this paper, the characteristics of three models such as the simplified overall biological model, simplified anatomical model and voxel model, as well as the calculation method of dose coefficient are analyzed and discussed. Suggestions for further evaluation of dose assessment of non-human species are proposed.

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